The animal immune system is a sophisticated weapon in the fight against foreign invaders, which include harmful bacteria, viruses and fungi. The first part of the immune system is the non-specific defense that attempts to prevent all unknown substances from entering the body. In a human, this includes skin, earwax and mucous membranes. If this defense is compromised, usually by a cut on the skin, an inflammatory response occurs, adding heat to the area and clotting the blood to block the opening.
Any foreign particle that triggers an immune response is called an antigen. If an antigen is able to make it past the first-line, non-specific response, the body targets the invader with a specific attack. First, the body rapidly makes copies of an antibody that can bind to the antigen. There are countless variations of antibodies in human blood, each with a shape that matches it to one specific antigen. The binding of an antibody to an antigen flags the invader for destruction by other immune system cells.
Scientists utilize the ultra-specific nature of the immune response to create tests for certain diseases. This will be the basis for our lab, in which an infection will spread throughout the classroom through "bodily fluids." When testing for a certain disease, the matching antibodies are added to the subject's blood samples. If the patient has the infection, the antibodies will bind to the antigens. Next, secondary antibodies are added to the sample. Secondary antibodies are isolated by exposing one species to antibodies from a different species. The exposed animal treats the antibodies as a foreign invader, creating new secondary antibodies to bind to the original ones. These secondary antibodies, attached to enzyme, are then added to the blood sample, binding to the original antibody-antigen complex if disease is present.
The method is called Enzyme-linked Immunosorbant Assay (ELISA) and can be useful in many different applications. It can be used to test for HIV, SARS or any other type of cantagious infection (but not genetic diseases). It can also be used for pregnancy testing by targeting the hormones released by the fetus in a mother's womb.
We will record the name of the person with whom we swapped bodily fluids, as well as the time the exchange occurred. At the end, we will use ELISA to determine if and to what level we have the disease. Using the fluid-swap logs, we will hopefully be able to figure out who initially had the disease and, therefore, caused the epidemic.
Results:
Based on the chart, we have concluded that Chloe and Taylor were the original disease-carriers. Every person they came in contact with ended up with a full-blown version of the disease, so they must have started the pandemic. There are several sources of error that could potentially screw up the experiment, but we were careful to avoid them. If the wells are not completely washed after the second antibody is added, there could be a false positive. Enzyme may remain in the well even if the second antibody did not bind. The same could occur if the primary antibody is not fully washed out. The second antibody would still bind, and a false positive would also occur. Finally, it is possible for to people to analyze the color of the liquid differently. What appears blue to one person may appear light blue to another. Luckily, although the lab was probably not perfecct, we were able to find the two individuals who began the spread of the disease.
